/*
 * Artificial Intelligence for Humans
 * Volume 2: Nature Inspired Algorithms
 * Java Version
 * http://www.aifh.org
 * http://www.jeffheaton.com
 *
 * Code repository:
 * https://github.com/jeffheaton/aifh
 *
 * Copyright 2014 by Jeff Heaton
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * For more information on Heaton Research copyrights, licenses
 * and trademarks visit:
 * http://www.heatonresearch.com/copyright
 */
package com.heatonresearch.aifh.evolutionary.sort;

import com.heatonresearch.aifh.evolutionary.genome.Genome;
import com.heatonresearch.aifh.evolutionary.train.EvolutionaryAlgorithm;

import java.util.Comparator;

/**
 * Sort the gnomes for species.  Sort first by score, second by birth generation.
 * This favors younger genomes if scores are equal.
 */
public class SortGenomesForSpecies implements Comparator<Genome> {

    /**
     * The trainer.
     */
    private final EvolutionaryAlgorithm train;

    /**
     * Construct the comparator.
     *
     * @param theTrain The trainer.
     */
    public SortGenomesForSpecies(final EvolutionaryAlgorithm theTrain) {
        this.train = theTrain;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public int compare(Genome g1, Genome g2) {
        final int result = this.train.getSelectionComparator().compare(g1, g2);

        if (result != 0) {
            return result;
        }

        return g2.getBirthGeneration() - g1.getBirthGeneration();
    }

}
